Hypertension as a health concern in children was evaluated in the 1960's and epidemiologic studies established that Stage I essential hypertension is more common than suspected. In the junior high school age and older, the focus begins to shift to essential hypertension and treatment with pharmacologic or non-pharmacologic therapy to reduce blood pressure below the 95th percentile for the particular age group. On November 21, 1997, the FDA Modernization Act (FDAMA) was enacted. In this was a draft list of drugs for which pediatric information might be useful. Ziac and Zebeta are included in this list and, with their excellent 24-hour blood pressure control and side effect profiles comparable to placebo and 24-hour blood pressure lowering effect, would be good additions to the armamentarium of drugs used in treating childhood hypertension. The objective of this study is to determine the pharmacokinetic profiles of Ziac (bisoiprolol fumarate/hydrochlorothiazide) and Zebeta (bisooprolol fumerate) in patients 8 to 17 years of age, with hypertension.